新型冠状病毒进化与变异

本文分析了新型冠状病毒(SARS-CoV-2,新冠病毒)的进化来源及刺突蛋白(spike protein, S)基因的突变情况。从GenBank数据库中下载相关病毒全基因组序列及S基因序列,运用DNAMAN 9.0、MEGAX等生物信息学软件,进行多序列比对,构建系统进化树,并统计S基因位点突变情况。分析结果提示,新冠病毒不可能来源于已知的6种人冠状病毒,相较于穿山甲,新冠病毒来源于蝙蝠的可能性更大。S基因的突变率应该和新冠病毒的流行时间及感染人数密切相关。未来,类似于SARS、MERS和新冠病毒这样由动物传播至人的冠状病毒可能还会出现,其流行趋势将取决于其致病性和变异性。     

功能性新型冠状病毒RBD结构域在毕赤酵母表面的展示*

目的:设计并构建新型冠状病毒(SARS-CoV-2)受体结合结构域(receptor binding domain,RBD)在毕赤酵母表面的展示体系,并对表面展示的RBD进行功能性评价,从而为以RBD为靶点的高通量药物筛选平台奠定基础。方法:将四种锚定分子与新冠病毒RBD融合,电转化至毕赤酵母中;通过细胞免疫荧光分析,筛选能够成功展示RBD的锚定系统;进一步分析其与血管紧张素转化酶2(angiotensin-converting enzyme 2,ACE2)受体的亲和力,证明展示在细胞表面RBD分子的功能。结果:仅Sed1p锚定分子能够有效呈递RBD至毕赤酵母细胞表面,展示效率约为70%;亲和力分析结果表明,ACE2受体和表面展示RBD的亲和力(K_D = 30.42 nmol/L)与溶液中RBD的亲和力(K_D = 16.00 nmol/L)较为接近。结论:这一体系能够在毕赤酵母表面高效地展示具有生物学功能的RBD,可用于抗新冠病毒RBD药物的高通量筛选和评价。     

庆阳市本土新冠病毒Omicron变异株的全基因组特征分析

本文将高通量测序技术应用于新型冠状病毒感染（COVID-19）的疫情防控当中,从基因组水平上了解新型冠状病毒（SARS-CoV-2）的分子学特征及变异情况,从而为疫情的防控提供科学的参考及准确的研判依据。我们选取2022年8月-9月庆阳市报告的新冠疫情本土感染者标本作为研究对象,对标本进行核酸检测和病毒全基因组测序并进行序列比对,使用MEGA分析软件基于邻接法构建病毒进化树,从而了解病毒的分子学特征及相关性。本研究所选取的9例病例均为普通型病例,核酸检测Ct值均较低。Nextclade分型结果显示：9条序列均属于21L型Omicron变异株;Pangolin分型结果显示：9条序列均处于Pangolin谱系中的BA.2.76进化分支上。与武汉参考株Wuhan-Hu-1(NC＿045512.2)相比,9条SARS-CoV-2序列的核苷酸同源性中位数为94.6%,核苷酸突变类型包括76～78个替换突变和3处缺失突变,氨基酸突变位点共涉及10个基因编码框,按氨基酸错义突变总数由多到少依次为：S蛋白区,ORF1ab区,N蛋白区,M蛋白区,E蛋白区和ORF3a、ORF6、ORF8、ORF9b区。进...     

乙型肝炎病毒逆转录酶区基因序列准种与变异特点

乙型肝炎病毒(Hepatitis B Virus,HBV)P基因编码产物从功能上分为末端蛋白(1～178aa)、间隔区(179～336aa)、逆转录酶区(337～682aa)和RNA酶H区(683～816aa),各区有相应的生物学功能;逆转录酶区包含S基因主蛋白编码区.近年来的研究提出HBV感染者体内存在有准种[1,2]的假说.我们以逆转录酶区序列为研究靶区域,应用聚合酶链反应(PCR)技术扩增慢性乙型肝炎患者血清中的靶基因序列,随机选择克隆测序,比较其结果,证明了HBV准种特点的存在,并发现多种基因突变形式.     

人冠状病毒NL63受体结合区蛋白的原核表达纯化与鉴定

人冠状病毒NL63受体结合区蛋白是其免疫学诊断和疫苗研究的主要靶点,在受体吸附、病毒进入细胞及膜融合中起关键作用。本研究在E.coli系统中进行人冠状病毒NL63受体结合区(RBD)大、小蛋白的表达纯化,并对其进行免疫学鉴定。首先密码子优化设计合成了HCoV-NL63的RBD大片段(RL:232-684aa)与小片段(RS:476-616aa)的编码基因,并将其克隆进硫氧还蛋白表达载体pM48,构建了人冠状病毒NL63的受体结合区蛋白(RBD)大(RL)、小(RS)片段与硫氧还蛋白的融合表达质粒;转化E.coli BL21pLys S,利用IPTG进行诱导表达,用镍亲和层析对蛋白进行纯化,并以表达HCoV-NL63RL与RS蛋白的重组痘苗病毒免疫小鼠血清对重组蛋白进行免疫印迹鉴定。结果表明在37℃,0.8mM IPTG诱导4h时,蛋白表达量达到最高,融合蛋白主要以包涵体形式表达,纯化后纯度可达95%以上。Western blot显示,两个融合蛋白均与痘苗病毒(天坛株)表达的HCoV-NL63RL与RS蛋白免疫的小鼠血清发生特异性反应。本研究首次在国内用原核系统表达纯化并鉴定了人冠状病毒NL63受体结合区大小蛋白(RL和RS),为人冠状病毒NL63感染的免疫学检测与疫苗研究提供了基础。     

中国南瓜曲叶病毒DNAA的克隆及其全序列

对引起我国南瓜曲叶病的病毒分离物DNA的克隆和序列分析表明,中国南瓜曲叶病毒DNA A由2741个核苷酸组成,共编码6个开放阅读框(ORF),其中病毒链有2个ORF：AV1(256aa)和AV2(140aa),AV1为外壳蛋白基因;病毒链的互补链有4个ORF,AC1(243aa)编码复制酶基因,AC2(134aa)编码反式激活蛋白,AC3(136aa)和AC4(172aa),该病毒属于旧世界Begomoviruses,是一个粉虱传播的联体病毒。     

新型冠状病毒S蛋白RBD肽段的原核表达与纯化

目的:利用原核系统对新型冠状病毒S蛋白的受体结合域(RBD)肽段进行克隆、表达和纯化,制备高纯度的RBD肽。方法:在RBD肽段N端加入肠激酶位点序列(DDDDK),对应的核酸序列参照原核系统表达偏好进行全基因合成,构建pET-DsbC-RBD融合表达载体,通过原核表达和亲和纯化获得DsbC-RBD融合蛋白,用肠激酶对融合蛋白进行酶切和二次亲和纯化,获得高纯度新冠病毒S蛋白RBD肽。结果:构建了pET-DsbC-RBD表达载体,融合蛋白DsbC-RBD在大肠杆菌中实现了高效表达,经亲和层析纯化,重组融合蛋白DsbC-RBD相对分子质量为58×103,纯度约90%。用肠激酶对融合蛋白进行酶切,酶切效率近100%,通过二次亲和纯化获得了RBD肽,相对分子质量为25×103,纯度92%以上。结论:利用原核表达系统获得可溶性DsbC-RBD融合蛋白,采用亲和纯化和肠激酶酶切联用的方法制备获得高纯度的新冠病毒S蛋白RBD肽,为后续抗体制备和抗病毒药物筛选奠定了基础。     

全球新型冠状病毒变异株研究进展

截至2021年5月11日,基于Pango命名法,依据新型冠状病毒(SARS-CoV-2)的基因组变异变迁将其划分为1281种亚型或分支.而SARS-CoV-2刺突(spike,S)蛋白的变异直接影响病毒的生物学功能.2020年下半年至今,全球多个国家和地区监测发现SARS-CoV-2的S蛋白发生氨基酸突变,特别是受体结合区或单克隆抗体结合位点氨基酸突变引起病毒的传播力和致病力改变以及部分免疫逃逸等.世界卫生组织将重要变异株划分为"关切变异株(variant of concern,VOC)"和"关注变异株(variant of interest,VOI)".其中,VOC 有4个,分别是 VOC 202012/01、501Y.V2﹑P.1 和 B.1.617;VOI 有6个,分别是 CAL.20C、P.2、B.1.526、B.1.525、B.1.616和P.3.一些氨基酸突变在多个VOC和VOI病毒株中交叉出现或同时出现,E484K/Q等重要氨基酸突变引起的部分免疫逃逸导致全球现有疫苗免疫效力下降,但现有新冠疫苗对VOC和VOI变异株仍然有效.本文通过对SARS-CoV-2变异株流行概况及S蛋白重要氨基酸突变特征进行归纳分析,为新冠病毒变异株的监测、防控和二代疫苗的研制策略提供科学参考.     

冰核细菌Erwinia ananas 110冰核基因克隆和序列分析*

从作者自行分离的冰核细菌(Erwinia ananas 110)中克隆到我国第1个细菌冰核基因,并完成其序列测定和分析。所克隆基因编码区全长3921bp,编码1306aa,氨基酸序列明显分为3个区即N-端(161aa)、C-端(41aa)的单一序列区和中部的高度重复序列R区(1104aa),以16氨基酸为重复单元的R区占整个编码序列的84.5％。序列分析表明我们所克隆的基因为一个新冰核基因,将其命名为iceA,该基因已在GenBank上登录,登录号为:AF387802。     

丙型肝炎病毒NS2-3蛋白酶基因在Sf9昆虫细胞中的表达

丙型肝炎病毒(hepatitis C virus,HCV)为单股正链RNA病毒,其基因组长约9.5kb,5'端和3'端各有一个长约345bp和60bp的非编码区,编码区含一个大开放读码框架,编码3 010aa～3 033aa残基的多蛋白前体.     

六种藓类植物茎的比较解剖学研究

通过对6种藓类植物,即褶叶青藓(Brachythecium salebrosum(Web.et Mohr.)B.S.G.)、湿地匐灯藓(Plagiomnium acutum(Lindb.)Kop.)、侧枝匐灯藓(Plagiomnium maximoviczii(Lindb.)Kop.)、大凤尾藓(Fissidensnobilis Griff.)、大羽藓(Thuidium cymbifolium(Doz.et Molk.)B.S.G.)和大灰藓(Hypnum plumaeforme Wils.)嫩茎和老茎的石蜡切片和显微观察发现,同一藓类植株的嫩茎和老茎,茎结构稳定,不同种藓类植物茎横切面具有不同特征.植物体茎横切面形状、表层细胞的层数、细胞大小和细胞壁厚薄、皮层细胞大小和形状、中轴的有无以及比例等特征可以作为藓类植物的分科分类依据之一.     

Photoregulation of seed germination of wild-type and of an aurea-mutant of tomato

Seed germination of an aurea mutant of tomato ( Lycopersicon esculentum Mill.) is promoted by continuous irradiation with red, far-red or long-wavelength far-red (758 nm) light as well as by cyclic irradiations (5 min red or 5 min far-red/25 min darkness). Far-red light applied immediately after each red does not change the germination behaviour. Seed germination of the isogenic wild-type, cv. UC-105, is promoted by continuous and cyclic red light while it is inhibited by continuous and cyclic far-red light and by continious 758 nm irradiation. Far-red irradiation reverses almost completely the promoting effect of red light. The promoting effect (in the aurea mutant) and the inhibitory effect (in the wild-type) of continuous far-red light do not show photon fluence rate dependency above 20 nmol m⁻² s⁻¹. It is concluded that phytochrome controls tomato seed germination throgh low energy responses in both the wild type and the au mutant. The promoting effect of continuous and cyclic far-red light in the au mutant can be attributed to a greater sensitivity to P_fr.     

Cause of Senescence of Nine Sorts of Flowers

The levels of endogenous phytohormones and respiratory rate in nine sorts of flowers such as Cymbidium faberi Rolfe, Nopalxochia ackermannii Kunth and others were investigated both at full bloom and senescence and meanwhile the effect of exogenous phytohormones on prolonging the blossoms and promoting ethylene production were tested. There is a high content of endogenous ethylene in all the long-lived flowere, about 3–16 folds higer than the short-lived ones. There is a high level of ABA at full blooming flowers of short-lived flowers, in which there is no or only some cytokinins in it, but the ratio of CTK (6BA+zeatin)/ABA is smaller(l.7). The endogenous ABA reached a much higher level at senescence in all nine sorts of flowers, so it is reasonable to consider that it is ABA which plays an important role of regulation in controlling flower's senescence. There is a much higher level of GA3 and zeatin in the long-lived flowers which is not demonstrated in the shortlived ones. The respiratory rate is one of the factors controtling the longevity of flowers, but it does not play a decided role. Application of 6BA and zeatin prolongs distinctly orchid’s longevity, however exogenous IAA through the promotive action on ethylene production, evidently extends the longevity of the flowers of the Nopalxochia ackermannii Kunth.     

Interconnection of parameters of regulation system of lipid peroxidation and of morphophysiological parameters of mouse liver

A complex analysis of seasonal fluctuations of the mean group parameters of the system of regulation of lipid peroxidation has been performed in liver of Balb/c mice. Association of lipid characteristics and morphophysiological parameters is studied in the Balb/c mouse liver. An inter-connection is revealed between the liver index and the amount of lysoforms of phospholipids, the scale and character of the interconnection differing essentially depending on proportion of phos-phatidylcholine in mouse liver phospholipids.     

龙胆科药用植物化学成分的研究现状

龙胆科植物在我国的分布范围很广,且多数为药用植物,其多数种属的药用植物,至今其化学成分尚未被系统研究。综述了目前龙胆科药用植物的化学成分的研究现状及一般提取方法,对近年来发现的环烯醚萜及裂环烯醚萜类化合物进行了总结,为本科药用植物的更深入研究提供了参考。     

Physiological characteristics of various species of strains of carboxydobacteria

Seven strains of aerobic carbon monoxide-oxidizing bacteria (carboxydebacteria) when growing on CO as sole source of carbon and energy had doubling times which ranged from 12–42 h. The activity profiles obtained after discontinuous sucrose density gradient centrifugation indicated that the CO-oxidizing enzymes are soluble and the hydrogenases are membrane-bound in all strains examined. The CO-oxidizing enzymes of Pseudomonas carboxydohydrogena, Pseudomonas carboxydoflava, Comamonas compransoris, and the so far unidentified strains OM2, OM3, and OM4 had a molecular weight of 230,000; that of Achromobacter carboxydus amounted to 170,000. The molecular weights of the CO-oxidizing and H₂-oxidizing enzymes turned out to be identical. The cell sonicates were shown to catalyze the oxidation of both CO and H₂ with methylene blue, thionine, phenazine methosulfate, toluylene blue, dichlorophenolindophenol, cytochrome c or ferricyanide as electron acceptors. Methyl viologen, benzyl viologen, FAD⁺, FMN⁺, and NAD(P)⁺ were not reduced. The spectrum of electron acceptors was identical for all strains tested. Neither free formate, hydrogen nor oxygen gas were involved in the CO-oxidation reaction. Methylene blue was reduced by CO at a 1:1 molar ratio. The results indicate that CO-oxidation by carboxydobacteria is catalyzed by identical or similar enzymes and that the reaction obeys the equation CO+H₂OCO₂+2H⁺+2e^- as previously shown for Pseudomonas carboxydovorans.Dedicated to Otto Kandler remembering almost three decades of enjoyable cooperation     

Modulation of allostery of pyruvate kinase by shifting of an ensemble of microstates

Since the introduction of the concepts of allostery about four decades ago, much advancement has been made in elucidating the structure-function correlation in allostery. However, there are still a number of issues that remain unresolved. In this review we used mammalian pyruvate kinase (PK) as a model system to understand the role of protein dynamics in modulating cooperativity. PK has a triosephosphate isomerase (TIM)(α/β)₈ barrel structural motif. PK is an ideal system to address basic questions regarding regulatory mechanisms about this common (α/β)₈ structural motif. The simplest model accounting for all of the solution thermodynamic and kinetic data on ligand-enzyme interactions involves two conformational states, inactive E^T and active E^R. These conformational states are represented by domain movements. Further studies provide the first evidence for a differential effect of ligand binding on the dynamics of the structural elements, not major secondary structural changes. These data are consistent with our model that allosteric regulation of PK is the consequence of perturbation of the distribution of an ensemble of states in which the inactive E^T and active E^R represent the two extreme end states. Sequence differences and ligands can modulate the distribution of states leading to alterations of functions. The future work includes: defining the network of functionally connected residues; elucidating the chemical principles governing the sequence differences which affect functions; and probing the nature of mutations on the stability of the secondary structural elements, which in turn modulate allostery.     

（鱼句）亚科花（鱼骨）型鱼类骨骼系统的比较

对我国花型Hemibarbuspattern鱼类作了骨骼系统比较,结果表明,此类型鱼类脑颅较长,副蝶骨平直或稍弯曲,眶蝶骨腹纵嵴发达(铜鱼Coreius septentrionalis例外),下颞窝和咽突中等大,基枕骨后突发达;脑颅中的上筛骨的后突、侧筛骨的外筛突,蝶耳骨的外突、上耳骨的后突、围眶骨和后颞窝等均有明显的差异;咽颅中的舌颌骨、尾舌骨、鳃盖骨和下咽齿的列数等又有显著的区别;附肢骨骼中的腰带骨、脊椎骨中的复合神经骨和第4椎骨腹侧的悬器等也有不同之处。据此,这些差异和区别可作为属间或种间的分类依据。